Servlet过滤器简介与字符串过滤

一.Servlet过滤器的用途
(1)用户认证与授权管理
(2)统计Web应用的访问量和访问的命中率,形成访问报告.
(3)实现Web应用的日志处理功能.
(4)实现数据压缩功能.
(5)对传输的数据进行加密.
(6)实现XML文件的XSLT转换.

 

二.实现Servlet过滤器
编写实现javax.servlet.Filter接口的类
配置Servlet过滤器

 

EncodingFilter.java

package com.deng.util;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;public class EncodingFilter implements Filter {public void destroy() {}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {request.setCharacterEncoding("UTF-8");response.setCharacterEncoding("UTF-8");chain.doFilter(request, response);}public void init(FilterConfig filterConfig) throws ServletException {}}

 

web.xml

<filter> <filter-name>EncodingFilter</filter-name> <filter-class>com.deng.util.EncodingFilter</filter-class> </filter> <filter-mapping> <filter-name>EncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>